The pectoralis minor is a thin, flat muscle found immediately under the pectoralis major. This is the smaller of the two pectoral muscles, or muscles of the chest. This muscle extends from three origins on the third, fourth, and fifth ribs on each side of the ribcage to a coracoids process of the scapula or shoulder blade. The origins of the muscle are all lateral to the costal cartilages. Primary actions include the stabilization, depression, abduction or protraction, upward tilt, and downward rotation of the scapula. When the ribs are immobilized, this muscle brings the scapula forward, and when the scapula is fixed, it lifts up the rib cage. There are two parallel pectoralis minor muscles, one on each side of the sternum. Both pectoralis muscles work with the serratus anterior muscles to create a full range of movement for the scapula. Pectoralis minor receives its arterial supply from the thoracoacromial trunk's pectoral branch. Innervation or stimulation comes from the clavicular head at C8 and T1 and the medial pectoral nerves.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Pectoralis minor